OFFSET
1,4
COMMENTS
This sequence is nondecreasing. Indeed, let c(n) be the concatenation of the first n terms of this sequence and d(n) the number of decimal digits of a(n). For n > 2, a(n) divides c(n-1), so a(n) is a proper divisor of c(n-1)*10^d(n) + a(n) = c(n), and thus a(n) <= a(n+1). - Danny Rorabaugh, Nov 27 2018
a(11) is too large to show in the Data section. It is
3712386376700143863674244290498850423358843221880592692719912374621255667\
1462122474809683295014111961440729353089757331237462125566714621224748096\
8329501411196144072935308975733041248737518890487374158269894431671370653\
81357645102991911.
MATHEMATICA
FromDigits /@ Nest[Append[#, IntegerDigits@ Divisors[FromDigits[Join @@ #]][[-2]] ] &, {{1}, {1}}, 8] (* Michael De Vlieger, Nov 26 2018 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
John Mason, Nov 26 2018
STATUS
approved